The BBC is planning to cut its coverage of the G20 and the Oscars after spending more than £100,000 on the rescue in Chile.

The corporation expects to have to choose between sending political editor Nick Robinson or business editor Robert Peston to next month's G20 summit of world leaders in Seoul because it cannot afford both to travel.

Oscars coverage will have to be confined to BBC1's Breakfast show while fewer people will be sent to other big events, such as a climate change summit in Cancun, a Nato summit in Lisbon and the Davos World Economic Forum.

A memo from the BBC's world news editor Jon Williams said its "financial situation is serious" and added: "We are currently £67k beyond our agreed overspend of £500k; newsgathering's costs for Chile will exceed £100,000."

The memo, sent last week and obtained by the Guardian, added: "We will scale back editor deployments to the G20 — so either Robert or Nick, but not both."

Yesterday's coverage was led by Matt Frei, who interviewed the mother of the youngest miner, Jimmy Sanchez, in Spanish and Tim Willcox. It was broadcast throughout the day on the BBC News channel and streamed on the BBC website.

Mr Williams said there would be "consequences for other events in the coming months" as a result of the coverage from Chile. He said the Nato summit would suffer from "much reduced ambition".

The BBC said 4.8 million people watched the rescue on the 6pm news, and 5.3 million on the 10pm news.